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11/24/2003

FDA Approves Cialis for Erectile Dysfunction

Kate Traynor

The Food and Drug Administration (FDA) on Friday gave marketing approval to Eli Lilly and Co.'s phosphodiesterase type 5 (PDE5) inhibitor, tadalafil, for the treatment of erectile dysfunction.

Tadalafil, the third PDE5 inhibitor to earn FDA approval for this indication, will be marketed as Cialis. Lilly announced that the product will be available in pharmacies in early December.

Tadalafil will be sold as 5-mg, 10-mg and 20-mg tablets packaged in 30-count bottles. The recommended starting dosage for tadalafil for most patients is 10 mg taken with or without food before anticipated sexual activity, according to the product's labeling (PDF). Lower dosages are recommended for men concurrently treated with certain strong inhibitors of the cytochrome P-450 3A4 isoenzyme, such as ritonavir, itraconazole, or ketoconazole. A 5-mg-per-day starting dosage is recommended for men with moderate to severe kidney disease; these patients should take no more than 10 mg of tadalafil every 48 hours.

Coadministration of tadalafil and organic nitrates can lead to dangerously low blood pressure and is contraindicated. Likewise, tadalafil must not be administered to patients who take any alpha-adrenergic blocker, except tamsulosin 0.4 mg once-daily, because of the risk of hypotension.

The product is not recommended for patients who have suffered a myocardial infarction or stroke within the past six months. Men who have very low blood pressure, uncontrolled high blood pressure, unstable angina, severe liver disease, or the eye disorder retinitis pigmentosa should not take tadalafil.

In clinical trials, the most common adverse events reported by men who took tadalafil were headache, indigestion, back or muscle pain, flushing, and nasal congestion. Back and muscle aches usually occurred 12–24 hours after administration of the product and resolved within two days. In rare instances, clinical trial participants reported disturbances to color vision after taking tadalafil.

According to FDA, tadalafil is metabolized more slowly than other drugs in the class, with some tadalafil detectable in the body for more than two days after administration. FDA noted that no clinical trials have been conducted to compare the clinical efficacy of tadalafil and other PDE5 inhibitors.